Pipe used for drilling operations is joined in lengths to form long drill strings. The joints of the pipe are generally threaded. Rubber bumpers sized to fit tightly over a pipe joint are used to protect the joint. The cylindrical pipe protectors have an inner diameter which is generally stretched to be installed on the pipe and fits very tightly around the pipe. Also, rubber pipe protectors have been used at other points on a length of pipe other than at joints to absorb shock.
The pipe protectors are rather large, bulky pieces of rubber. The internal diameter of the pipe protector is usually smaller than the pipe surface to be covered. The installation requires equipment which will stretch and expand the internal diameter of the pipe protector.
Usually the pipe protector is stretched over a short mandrel or transfer sleeve that has a smooth, low friction outer surface. The transfer sleeve has an outer diameter slightly larger than the outer diameter of the joint of the pipe. After stretching the pipe protector and sliding it on the transfer sleeve, the pipe protector is then ready to be installed on the drill pipe. A hydraulic pressured gun is usually used to transfer the pipe protector from the transfer sleeve to the pipe joint or area.
The installtion units of the prior art are hydraulic. Some use water pressure which limits the pressure to 250 psi. Other units use a hydraulic system with a cylinder that pressurizes the fluid to 1000 psi. The hydraulic units have a typical piston and cylinder arrangement.
The shaft extends through a spider plate which is mounted on the cylinder. A rubber bumper rests on the mounting of the spider plate. The installation unit is loaded with a pipe protector, transfer cone and transfer sleeve respectively on the shaft. The parts are secured on the shaft with a collar or plate placed just above the transfer sleeve.
The piston is actuated by the inflow of hydraulic fluid to move downwardly in the cylinder. As the piston moves down, the transfer cone is forced into the pipe protector. The taper of the cone permits it to slide into the inner diameter of the pipe protector and as the piston moves downward it forces the larger diameter of the cone into the pipe protector thereby stretching the internal diameter of the pipe protector.
The pipe protector then is forced over the transfer sleeve which is approximately the same diameter as the largest diameter of the cone. During the downward movement the spider plate contacts the circumference of the transfer cone. The pipe protector maintains a position to top of the spider plate as it is forced over the cone and sleeve. The spider plate expands around the taper of the cone during operations. In the prior art one spring circles the outside of the spider plate.
After the pipe protector was forced over the transfer sleeve the collar or plate securing the operating parts on the shaft is removed. The transfer sleeve loaded with the pipe protector is ready for use.